Improving Postural Stability: A Quasi-Sliding Mode Control Approach for Bio-Mechanical System

Human gait and postural stability are essential for daily activities and are influenced by various biomechanical and control factors. This article analyzes a single-link biomechanical model to improve balance using quasi-sliding mode control (QSMC). Traditional methods like PID controllers and feedback linearization require high control signals and input torque, leading to inefficiency and high energy consumption. While sliding mode control (SMC) handles nonlinearity and uncertainty well, it suffers from chattering and high-frequency oscillations in the control input. To address this, we employ QSMC, which uses a continuous control function rather than the discontinuous one of SMC, thereby reducing chattering. Our findings show that QSMC achieves convergence in 5-6 seconds, with a significant reduction in reference input torque to 135 Nm, enhancing efficiency and lowering energy consumption, mechanical stress, and system wear. Compared to previous methods, QSMC offers a more efficient solution for postural control in biomechanical systems.